Fuel pump



April 29, 1930. c. R. ALDEN 1 1,756,145

FUEL PUMP Filed Jan. 3, 1928 2 Sheets-Sheet 1 17 I 55 Z6 1' .l. 14 31 CarroM Jddaw, 9 I m M.

C. R. ALDEN April 29, 1930.

jvzieflo r- CajrroLZ f1? fllde lllll Illllll FUEL PUMP Filed Jan. 3, 1928 III III lllllll II II lllllll Patented Apr. 29, 1930 NITED STATES PATENT OFFICE CARROLL R. ALDEN, F DETROIT, MICHIGAN, ASSIGNOR T0 EX-CELL-O AIRCRAFT AND TOOL CORPORATION, OF DETROIT, MICHIGAN, A CORPORATION FUEL PUMP C Application filed'J'anuary 3, 1928. Serial No. 244,077.

This invention relates generally to improvements in fuel pumps for forming the trol valve in charges for internal combustion engines, and more particularly to the construction of a cona pump for an engine of the Diesel type. u

In the operation of fuel pumps of the above type, the injection of fuel oil under pressure into the engine cylinder takes place during the expulsion stroke of the pump piston and is terminated or cut off by suddenly decreas ing the pressure within the pump cylinder. This is usually effected by mechanically opening a valve which allows the oil under high pressure in the pump cylinder to be by-passed into an auxiliary chamber whichis usually filled with fuel oil. It has been found in practice that this sudden release of pressure and vthe initial rush of oil at high velocity into a body of oil in a static state causes considerable noise or knocking? In addition the initial flow of oilthrough the by-pass valve at high velocity causes such impingement of the oil particles as to result in the formation of hub l of the bles of oil vapor. Thiscondition is particularly disadvantageous where the same valve is used as an'intake valve, there being in such construction a tendency to draw the compressible vapor bubbles back into the pump cylinder in the next intake stroke of the pump Piston. Y

The primaryobject of the present invention is to provide a Diesel engine fuel pump having anew and improved valve structure for efficiently controlling the point of cutoff of fuelcinjection by releasing instantaneously the pressure in the pump cylinder with out the usual knocking and by preventing any back flow into the pump cylinder of oil carrying vapor or other compressible gases. 1

Another object is to provide a novel valve of the above character which also functions as an intake valve during the suction stroke pump piston and as a means for preventing back flow of the fuel oil to the-Supply line during injection of the oil into the engine cylinder.

In carrying out these objects; I provide separate outlet passageways from the fuel pump cylinder, one preferably leading to the OF. MICHIGAN constantly drained ehamberinto which the oil can flow freely and the other leading to the oil supply'line, two valves being provided to-control said passageways'and operable successively at the point of cut-off to allow a small volume of the oil to be by-passed-from.

the pump cylinder into said chamber and the remainder to flow back into said fuel sup ply line. The arrangement of the valves is such that the oil initially by-passed from the cylinder is positively entrapped in said chamher and thereby prevented from being drawn back into the cylinder during the succeeding suction stroke of the pump piston.

Other objects and advantages of the in-- vention will become'apparent from the following detailed description taken in connection with the accompanying drawings, in which, f

.Figure 1 is a vertical sectional view through a Diesel engine fuel pump equipped with a control valve embodying the features of the present invention.

Fig. 2 is a fragmentary view showing the valve structure in verti'cal'section;

Figs; 3 and 4 are enlarged views of the valve underdifferent operating conditions.

Fig. 5 is a section taken along line 5'5 of Fig. 4.

While the invention is susceptible of various modifications and alternative constructions, I have shown and will herein describe valvestru'cture is of the reciprocatory type and includes a casing 6 adapted to be secured to the Diesel engine adjacent the cylinder thereof to be supplied with fuel charges by the pump. A countershaft 7 driven in properly timed relation to the crank shaft of the engine is rotatably supported by the casing and carries a cam 8 which acts on a roller 9 toperiodically raise a vertical tappet member 10.

Seated in the upper end of the tappetis a piston 11 which reciprocates in a cylinder 12 provided by a block 13 threading into a solid metal head 14 on the casing 6. A strong com pression spring 15' acting against the block serves to move the piston downwardly on its suction stroke-as permitted by the rotation of the cam 8 after itshigh point 16 has passed the roller 9.

The pump cylinder communicates through a narrow duct 17 in the head 14 with a pres.- sure chamber 18 which is adapted for com- 'munication with the cylinder of the Diesel engine through the central bore in a plug 19 and a tubular conduit- 20.. The flowpf oil through the bore is controlled by an automatically operable valve 21 preferably of the puppet type having a. spring pressed member mounted for reciprocationtoward and from a seat in the plug 19. 1

Fuel oil is admitted to the pressure chamber during the suction ordownward stroke of the piston 11 and is expelled therefrom during the upward stroke, being thereby injected under pressure into the engine cylinder through'the val 211or by-passed out of thechamber through auxiliary passagewa'vs controlled by the valve structure generallydesignated by the numeral 22.

In the present instance this valve structure comprises two valves formed by two coaxially arranged and relatively movable members 23 and 24 disposed in a central bore 25 of a block 26 which is secured by a screw 27 in a counterbored recess in the head 14.

The outer member 23 together with its stationary seat constitutes the main by-pass valve-28 for"controlling the flow of oil out of the chamber 18 after termination of the 'oil' injection and in the present instance also operates tocontrol the, admission of oil into" the chamber 18 as well as to prevent the flow therefromduring injection. At its lower end the member 23 has a stem of circular cross section (Fig? mounted for reciprocation in the bore 25. 1 A head 29 is formed at the upper end of the member with down- 'wardly converging sides which are adapted 5 to be seated on the upper peripheral edge of the bore 25 which is flared outwardly slightly at its upper end. Thus-an annular passage 33 is formed around the member 23 3 within the borel25, communication between thls pas age and an annular chamber 31 being establishedthrough ports 32 formed in the block 26 so as to be'openfor all positions of the member 23. The chamber 31 is continuously supplied from a duct 33 with fuel oil preferably under a primary pressure somewhat above that of the atmosphere. It will be seen that when the valve member 23 is raised from its seat (Fig. 5) a'relatively'la'rge passageway is provided for the flow of oil in -either directionbetween the supply duct 33 and the chamber 18,'the direction of flow being dependent upon the relative pressures at the two points. -,The passage 30, the ports 32 pletely filled with oilat'all times during the operation of the pump. a

Preferably the valve member24 is formed with a portion fluted as shown in Fig. 5

and mounted for reciprocation in a central bore 34 which extends axially through the member 23. At its lower end the member 24 has converging surfaces 35 adapted to -be seated on the upper peripheral edge of an and the chamber 31 are intended to be com-- opening defined bv shoulders on the memher .23 at the lower end of the'bore 34. A

:stem 35 projects through the opening to a point slightly below the lower end of the member 23. Projecting upwardly through the bore 34 is ashank '36 ofsmallcross sec tion which carries at its upper enda plate 36? in which a compression spring 37 is seated. This spring acts betweeh the plate 36 and the lower end of the plug 19 there-- .by tendingto hold the valve member 24 seated which in turn operates to seat the'member 23. Acompres'sion spring 38 encircling end of the fluted portion of the member 24 and a retaining ring 39 tends to move the member 23 upwardly relative to the member the shank 36 and vacting between the upper 24, thereby raising the movable seat of the.

latter. Thus-, it will be observed that the member 24 together with its movableseat constitutes a valve 40 which hereinafter will betermed the auxiliary by-pass valve and which is adapted to control the .flow of oil from the chamber 18 past the fluted portion oft-he member 24 into a recess 41 below ithe bore 25. This recess is continuously drained by a duct 42 communicating therewith but separate from the fuel oil supply duct 33.

' In the present instance, the two valve memreciprocation by the lower end of a; blbck 46 herein threaded into the casing head 14. 1

A spring 47 encircling the block'46 tends to lower-the rod 43. v

Seated'on the member 45 and extending throughka central bore in the block- 46 is a plunger 48 having at its'extreme upper end aprojection 49 adapted to strike the stem 35 of the valve membe1'24 as the tappet rod 43 is raised. A cap 50 adjustably threaded on the end or the plunger 48 is ber 23 during the upward movementof the tappet rod 43 but subsequent to the time when the member 24 is engaged by the projection 49. -With this arrangement, it will be observed thatthe two valve members 23 and 24 are actuated successively as the tappet rod 43 is raised.

i 43 to determine, the expulsion stroke of the In the pump herein illustrated, two 'independent mechanical means are provided 'for controlling the movements of the tappet rod in one case, the point during piston 11 at which fuel oil will be injected into the engine cylinder and, in the other case, the point of cutoff, that is, the point at which injection ceases.

Hereinthepoint of injection is controlled by holdingthe'tappet rod 43 raised during the initialpartof the upward stroke of the piston 11, part of the charge in the pump cylinder being bypassed therefrom and then allowing the rod 43 to fall and close the valve 28. Referring to Fig. 1, the means herein emthe major portion of the suction ployed fdr this purppse comprises an arm 51 swingably mounted on a shaft 52 and carrying-a .roller 53 for following the surface of acam 54 on the countershaft 'i and a second roller 55 engagingthe lower end of the plung er 44. Thus, for any given setting of theaxis of the shaft 52, the cam 54 will operate the arm 51 so as to hold the valve 28 open during stroke of the piston 11'and for a predetermined interval after the pump piston has started on its exmovement of the stroke, strikes a pulsion be allowed to close. With this valve closed further displacement of the piston will force the oil in the pump cylinder. through the valve 21 into the engine cylinder.

The point of cut-01f, in the present embodiment, takes place in timed relation to the piston 11 and is effected by raising the tappet rod 43 which operates the a manner to be presently described in detail. The tappet rod 43 is raised through the medium of a lever 56 pivotal ly mounted at one end on a shaft 57 and having its other end connected to the tappet rod 10. Ilhis lever carries an adjustable stop 58 which, after the'plunger has progressed a predetermined distance on its expulsion collar 59 on the tappet rod 43 thereby raising the same.

The operation of the valve structure during one charge forming cycle of operation of the pump will now be described. Assuming that the pump piston is completing its suction or the valve 21 would be closed, the tappet 43 would be held raised as shown in F ig; 4 by the high portion of the cam 54. Thus the projection 49 would hold downward stroke,

' 4 the valve member 24 raised against the. action of the spring 37, the spring 38 then functioning to hold the member 23in raised position with the valve 40 closed and the valve 28 open.

stroke, after which the valve 28 will As soon as the piston 11 starts on its upward or expulsionfstroke, that is, when the point 60 on the cam 8 contacts the roller 9, the directionof flow of oil is reversed, oil in the chamber 18 being by-passed back through the open valve 28 into the supply duct 33. Since the valve 40 is held closed at this time by the action of the spring 38 and the pressure of the oil in the chamber 18 which exceeds that in the recess 41, no oil will be by-passed into the recess 41. Later in the expulsion stroke when the cam 54 has advanced sufficiently to allow the valve 28 to be closed by lowering of the tappet rod 43 thereby preventing further by-passing, the oil in the pump cylinder is placed under high pressure. Then the valve 21 opens automatically and a portion of the oil is forced into the engine. This condition of the pump is illustrated in Figs, 1 and 2. Injection of the oil at high pressure continues 'until the tappet rod 10 has been raised sufliciently to carry the stop 58 against the collar 59. This raises the-tappet rod 43 carrying the projection 49 against the stem 35 thereby raising the member 24 from'its seat, as shown in Fig. 3. At this instant the pressure of the oil in the chamber 18 acting on the upper end of the valve member 23 exceeds the force exerted upwardly on the member by the spring 38 and the primary pressure in thepassage 30; consequently the valve 28 is'held closed. With the valve 40 thus opened, the oil under high pressure in the chamber may flow along the fluted portion of the member 24 and around the stem 35 into the recess 41. Since the recess is preferably constantly drained and at atmospheric pressure, practically no resistance is offered to the flow of oil so that the initial rush through the valve will be at high velocity, the pressure within the chamber 18 being dissipated substantially instantaneously. Owing to the small size of the auxiliary valve 40 only a small volume of oil will be by-passed therethrough and any Vapor bubbles formed by the high velocity flow will be entrapped in the recess 41.

As soon as the pressure within the chamber 18 has been reduced to a point where it is overcome by the force of the spring 38 and the pressure within the passage 30, the valve member 23 isallow'ed to rise relative to the member 24. 7 As shownin Fig. 4, this closes the valve 40 and opens the valve 28 so that the fuel displaced by further rise of the pump piston 11 is by-passed through the valve 28 against the primary fuel pressure back into the supply duct 33. This mode of operation would be likely to take place when the engine is running at a rather slow speed. The valve member 23 may also be raised to open the valve 28 by the progressive upward movement of the tappet rod 43, such action taking place when the upper end of the cap 50 strikes the member This would probably be the case when the engine is running at higher speeds whenthe' pressure reduction within the chamber 18 does not take place, rapidly enough to allow for operation of the mem-' ber 23, as above described, before the cap 50 engages the member. Opening of the valve QSwhich provides a substantially greater pas sageway than theauxiliary valve instantaneously reduces the pressure within the chamber 18 to such a point as to allow the spring 38 to raise the member 23 away from the cap 5,0 (F ig. 4). By the reduction of pressure above described, further injection of oil into the engine cylinder is prevented and for the remainder ,of the eppulsion stroke of the pump piston oil is by-passed back into the supply duct 33 against'the primary pressure therein.

It will be seen that at the point of cut-ofi' in the pump cycle, the valves 40 and 28-are opened in quick succession and that substan- 'tially instantaneously thereafter the valve 40 'rence of knockin which usually takes placein pumps wherein cut-ofi' is efi'ected by initially by-passing the oil into a chamber already filled with oil in the static state. Since only as small [volume of the oil .flows through the valve 40, the primary pressure which is usual- 1y maintained in the supply chamber ,30 is not wast-ed. I i

When thehigh point 16 of the cam 8 passes the roller 9 so that the pump piston starts on its downward or'suctionstroke, the direction i of flow of the oil through the main valve .28 reverses flowing fromthe supply duct to the chamber 18. .At'this time the valve,membrs 23 and 24 are positioned as 'shown in Fig. 4 by, the combined action of the lever 56 and the cam 54 acting to hold the tappet rod 43 in-raised position. Since the valve 401s held closed by the spring 38 and by the excessive primary pressure under which the oil supply isplaced, none of. the turbulent 01lpreviously by-passed into the recess 41 can be drawn back through the valve 40into the. chamber 18. In other words, the auxiliary by-pass 40 allows for the flow of fluid in one direction onlysince any pressure difference between the chamber 18 and the recess 41 which would tend to permit a flow of the bypassed oil upwardly through the valve 40 would allow the spring 38 toraise the valve member 23 thus seating the member 24. Thus, all the oil which is apt to contain vapor bubbles is positively entrapped in the recess 41 and is kept separate from the re mainder of the oil by-pas's'ed subsequent to the point of cut-off.

It will be apparent that the valve construction above described is adapted to accomplish its intended functions in an eflicient and reliable manner and with the speed which is required in the operation of a fuel pump for the Diesel type of engine. All of theparts of the valve are simple in construction and adapted to be compactly assembled and conveniently operated from the engine to which the pump is applied.

I claim as my invention:

1. In apump for supplying liquid fuel to I the cylinder of-an internal combustionengine,

the combination of means providing a fuel receiving chamber adapted for communication with .said cylinder, a piston operated from said engine and adapted on one of its strokes to compress the fuel in said chamber, a second chamber normally filled with liquid fuel, a third chamber normally drained, a main by-pass valve member having a stationary seat and providing a valve which when opened establishes communication between, said first and second chambers, an auxiliary valve member extending axially of said first mentioned member and cooperating with a seat thereon to provide a valve controlling the flow of fuel from said first mentioned chamber to said third chamber, spring means acting on said auxiliary member and tending to hold both of saidtmembers seated, spring meanstending to move said main member relative to 531d auxiliary member whereby to maintain sa d auxiliary valve closed, and

' means operable during theexpulsion stroke of said piston to terminate the injection of fuel. into said cylinder including a mechanism driven from the engine and operating to, open said auxiliary valve whereby to relieve pressure in said first mentioned chamber.

2. In a pump for-supplying liquid fuel to the cylinder of an internal combustion engine, the combination of means providing a fuel receiving chamber adapted for communication with said cylinder, a piston operated from said engine and adapted on oneof its strokes to eompress the fuel in said chamber, a source of fuel supply, a second chamber normally drained and free from liquid fuel, two coaxially arranged and relatively movable members cooperating to provide two valves, one permitting .the flow of fuel from said first mentioned chamber into said second chamber.

only, said other valve permitting the flow of fluid in either direction between said first mentioned chamber and said source of supply,

and means actuated by said engine and operable at a predetermined point inthe expulinc piston to open said valves cylinder, a piston reciprocated by said engine and adapted on its expulsion stroke to compress the fuel in said chamber, a source of fuel supply, a second chamber, and means for terminating the injection of fuel into said cylinder by by-passing the fuel from the first t mentioned chamber including a main valve controlling the flow of fuel between said first mentioned chamber and said source of supply, an auxiliary valve controlling the flow of fuel from said first mentioned chamber to said second chamber, means operable at a predetermined point in the expulsion stroke of said piston to open said auxiliary'valve and said main valve successively, and means operable after a predetermined reduction in pressure in said first mentioned chamber to close said auxiliary valve.

4. In a pump for supplying fuel under pressure to the cylinder of an internal combustion engine, the combination of means providing a chamber for receiving liquid fuel and adapted for communication with said cylinder, a'piston" reciprocated by said engine and adapted on its expulsion stroke to compress the fuel in said chamber, a source of fuel supply, a second chamber, and means for terminating the inj ection-of fuel into said cylinder by by-passing the fuel from the first mentioned chamber including a main valve controlling the flow of fuel between said first mentioned chamber and saidsource of supan auxiliary valve controlling the flow of fuel from said first mentioned chamber to said second chamber, means operableat a predetermined point in the expulsion stroke of said piston to open said auxiliary valve,- and means operable after the pressure in said' first mentioned chamber has been reduced to a predetermined point to open said main valve and close said auxiliary valve. 7

5, In a pump for supplying fuel under pressure to the cylinder of aninternal conrbustion engine, the combination of means providing a chamber for receiving liquid fuel and adaptedfor communication with said cylinder, a piston recipr'ocated by said engine and adapted on its expulsion stroke to compress the fuellin said chamber, two independ' ent outlet passageways leading from said chamber, two coaxially arranged reciprocable valve members, one adapted to cooperate with a stationary seat to provide a main by-pass valve controlling one of'said passageways, said other member cooperating with a seat on said first mentioned member to provide an auxiliaryvalve controlling said other passageway,-spring mean acting between said members and normally tending to hold said auxiliary valve closed, and means operable at a predetermined point during the expulsion of fuel from said chamber to open said auxiliary valve. i

6. In a pump for supplying fuel under pressure to the cylinder of an internal combustion engine, the combination of means providing a chamber for receiving liquid fuel and adapted for communication with said' cylinder, a piston reciprocated by said engine and adapted on its expulsion stroke to compress the fuel in said chamber, main and auxiliary outlet passageways leading from said chamber, two coaxially arranged and relatively movable valve members each controlling one of said passageways, means opy erable during the expulsion of fuel from said chamber to actuate said members whereby to open said auxiliary and main passageways and means operating iiiin quick succession, dependently of said one of said members whereby to close said auxiliary passage.

' In a pump forsupplying liquid fuel to the cylinder of an internal combustion engine, the combination with a source of liquid fuel under pressure, a chamber for receiving fuel from said source of supply and adapted for communication with said engine cylinder, a

piston driven from said engine and adapted on its expulsion stroke to compress'the fuel in said chamber, a second chamber normally drained and maintained at a pressure lower than said fuel supply, a main valve controlling the flow of fuel between said first mentioned chamber and said source of supply, an auxiliary valve controlling the flow of fuel from said first mentioned chamber into said second chamber, and mechanism operable during the expulsion stroke of said piston to actuating means to move close said mam valve whereby to cause injeclets from said chamber, a main by-pass valve controlling one ofsaidoutlets, a pressure relief valve controlling said other outlet, and means operable at a predetermined point during the injection of fuel into said cylinder to open said pressure relief and by-pass valves successively and then close said pres: sure relief valve. 7

9 In a pump for supplying liquid fuel to the cylinder of an internal combustion englue, the comblnatlon with means providing a fuel receiving chamber, a member driven from said. engine and operable to compress fuel in said chamber and cause 1n ect1on thereof into said cyhnder, means providlng a second chamber normally filled with fuel oil,

means providing a constantly drained chamber, and means operable during the expul sion. of fuel from said chamber for terminating the injection of fuel into said. cylinder including a main bypass valve adapted when opened to establish communication between said first andsecond mentioned chambers, an

" driven from said engine and operable to auxiliary by-pass valve adapted when opened to establish communication between said first mentioned chamber and said constantly drained chamber, and mechanism operable to open' said auxiliary and main valves successively.

10. In a pump for supplying liquid fuel tothe cylinder of an internal combustion engine, the combination with means providing a fuel receiving chamber, a member drlven from said engine and operable to compress fuel in said chamber and cause injection thereof into said cylinder, means to cut 011' flow of fuel to said cylinder including main and auxiliary valves controlling independent outlets leading from said chamber, mechanism operable during the expulsion strokeof said member to open said auxiliary and main valvessuccessively, and means operable upon opening of saiduina-i-n valve to close said auxiliary valve.

11. In a pump for supplying liquid fuel to the cylinder of an internal combustion engine, the combination with means providing a fuel receiving chamber, a member driven from said engine and operable to compress fuel in saidchamber and cause injec-- tion thereof into said cylinder, a main outlet leading from said chamber to a source of fuel supply normally maintained under "pressure, an auxiliary outletadapted to connect said chamber with a. second chamber normally maintained at a pressure below that of said fuel supply, main and'auxiliary bypass valves cdntrolling said outlets respectively, and mechanism operable during the expulsion of fuel from said chamber to open said auxiliary and main valves successively.

12. In a pump for supplying liquid fuel to the cylinder of an 'internalvco'mbustion engine, the combination withineans providing a fuel receiving chamber, a member compress fuel in said chamber and cause in jection thereof into said cylinder, a main outlet leading from said chamber to. a source 'of fuel supply normally maintained under pressure, an auxiliary outlet adapted to connect said chamber with a second chamber nor.-

mally'lmaintained at a pressure below that of i'id fuel UPP Y; main" and auxil y bypass valves controlling said outlets respectively,

and mechanism operable during the expulsion of fuel from saidchamber to-open said auxiliary and main valves suecessively, and

means operable upon the-"opening ofsaid main valve to close said auxiliary valve.

1 3. Ina pump for supplying fuel to the cylinder of an-interna'l combustion engine, the comblnation of means providing a chamber,

for receiving liquid fuel a port-ion of which 1s to. be 1n]ected into said cylinder, a member drlven from said engine and movable in said chamber to expel fuel therefrom, main and auxiliary by-pass valves controlling separate outlets leadlng from sald chamber, and mechanism operable during the expulsion of fuel from sald chamber to open said main and auxiliary valves'succes'sively.

The combination with an lnternal combustlon engine fuel pump having a. chamber into which a charge of fuel is drawn and then expelled under pressure to cause a part thereof to be injected into a cylinder of said engine, of means to terminate the injection of fuel into said cylinder by by-passing the remaining part of said charge out of said chamber, said last mentioned means including a valve structure adapted to be actuated by said engine and operable to separate the initial and final portions-of the bypasspart of said charge.

15. The combination with an internal combination engine fuel pump having achamber into which a charge of fuel is drawn and then expelled under pressure to cause a part thereof to be injected into a cylinder of said engine, of means to terminate the injection of fuel into said cylinder byby-passing the remaining part of said charge out of said chamber, said last mentioned means includ- 

